Various types of work over and completion fluids with bridging agents are available and in use at the present time. Some are termed oil soluble and others are termed acid soluble, depending upon whether or not the bridging agents in the completion and work over fluids are soluble in oil or in acid. An important function of a completion and work over fluid is to seal off or temporarily plug the face of the producing formation in the well bore so that during the completion and work over operations fluid and solids in the fluid are not lost to the producing formation. Theoretically and ideally it is desired to accomplish this by depositing a thin film of solids over the surface of the producing formation without any loss of solids to the formation. Solids which are coated or deposited on the formation are generally termed bridging agents and temporarily bridge over the formation pores rather than permanently plugging the pores. The coating of bridging agent is then dissolved when the work over or completion operation is completed so that oil or gas may then be produced through the formation and into the well bore. A nondamaging work over and completion fluid is so termed in that it causes a minimum of permanent plugging of the formation pores by loss of solids, or particles in the completion and work over fluid to the producing formation. Other constituents are generally used in a work over and completion fluid including suitable additives or components to provide desired viscosity to the completion fluid and suspension of the solids therein as well as fluid loss control.